Conventional wired telephones coupled to the public switching telephone network (PSTN) may be used to make emergency calls. In many, if not most, communities, a public service access point (PSAP) is configured to receive emergency calls through the PSTN. When a caller dials 911 on a wired telephone coupled to the PSTN, the call is routed to the PSAP which also receives additional information such as the physical location (i.e., street and number) of the wired telephone making the call as well as the phone number of the telephone making the call. Thus, if the caller is unable to speak or cannot identify his or her location, the additional information provided to the PSAP may be used to dispatch the police, fire department, ambulance, and/or whatever service is appropriate given the situation.
Voice over IP (VOIP) telephones may use the Internet for telephone communication. A VOIP telephone may convert a voice signal into digital data that is transmitted over the Internet to a gateway that couples the Internet with the PSTN. The data is converted to a conventional voice signal at the gateway and provided to a recipient over the PSTN. An analogous process occurs in reverse where voice signals from a user of a conventional telephone coupled to the PSTN are provided to the gateway which converts the voice signals to digital data and then transmits the digital data to a receiving a VOIP telephone were the data is converted to an audio signal for a user of the VOIP telephone.
One difficulty with VOIP telephones is that, unlike regular wired telephones that have a fixed telephone number and physical location, a VOIP telephone may be moved to any location capable of providing an appropriate data interface to allow the VOIP telephone to exchange data with the Internet. Thus, a user of a VOIP telephone may move the phone from location to location without informing the telephone company (or anyone else) of the new location of the VOIP telephone. If the user of the VOIP telephone dials 911 in connection with an emergency, it is difficult, if not impossible, for the attendants at the PSAP to know the physical location of the caller without speaking with the caller and thus, the attendants at the PSAP may not know where to dispatch emergency services.
In addition, since the signal is provided over the Internet, it may be difficult, if not impossible, to know the particular PSAP that is appropriate for handling the emergency call. It is important that an emergency call be directed to an appropriate PSAP close to the physical location of the caller rather than a PSAP that is geographically distant from the caller. Otherwise, it may be difficult for a PSAP located in one state to know how to direct emergency services to a caller having an emergency in a different state. Accordingly, it is not just important to know the physical location of the caller, but it is also important to know the appropriate PSAP to which emergency calls should be directed for the caller.
It is desirable to provide a system that facilitates locating network devices and, in the case of VOIP telephones (or the equivalent), determines a local PSAP for a caller using a VOIP telephone to access emergency services.